Servo control mechanism for governor



May 27, 1958 c. H. FRICK ETAL 2,335,410

SERVO CONTROL MECHANISM FOR GOVERNOR Filed Dec. 2, 1953 2 Sheets-Sheet 1 g I 55 7 H 58 i I Fi- I H -71 /Z INVENTORS ATTORNEY SERVO CONTROL MECHANISM FOR GOVERNOR Charles H. Flick, Pontiac, and Vernon E. Schafer, Jr.,

Livonia, Mich, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application December 2, 1953, Serial No. 395,797

Claims. (Cl. 264-7) This invention relates to governors, and more particularly to governors having a droop characteristic with variation in the governed operating condition of the device associated therewith.

An object of this invention is to provide a governor with a servo-control mechanism operable to control the droop characteristic of the governor in response to changes in the governed operating condition.

A further and more specific object of this invention is to provide such a servo-control which is of simple, rugged and compact design for economical manufacture, eflicient operation and long operating life.

A still further object of this invention is to provide such a servo-control which is adaptable to replace manual speeder spring adjustment means in existing prime mover installations. This object is obtained by substituting a speed-responsive speeder spring plunger element which has adjustably extending from one end a pilot valve which is reciprocable within andcontrols hydraulic fluid inlet and relief ports opening into an axially extending bore within a piston which is reciprocable within the cylinder of the servo-control and takes the place of the adjustable spring seat of the manual control.

Other objects and advantages of the invention will become apparent from the following detailed description with reference to the drawings, in which:

Figure 1 is a broken sectional view of one type of governor to which our invention may be adapted, and showing the upper and lower portions of the governor in axially transposed relationship;

Figure 2 is a sectional view of the upper portion of the governor taken substantially on the line 2--2 of Fig.- ure 1, and showing the features of our invention as embodied therein.

Figure 3 is a sectional View of the lower portion of the governor taken substantially on the line 33 of Figure 1.

The governor mechanism shown in Figure 1 has a speed responsive centrifugal assembly rotatably mounted in a bell-shaped lower casing portion 10, a fuel feed control mechanism and speeder spring assembly housed in an upper casing portion 12, and a shaft interconnecting the rotating assembly with the fuel feed control mechanism and housed in an intermediate tubular casing portion 14. The variousportions of the casing may be cast integrally,

as shown, or may be cast separately and bolted or other-.

wise suitably secured to one another. A flange 11 formed on the bell-shaped casing member is adapted to be bolted or otherwise secured to the housing of the driving device.

The rotating assembly, as best shown in Figures land 3, includes a short shaft 18 having one end journalled in an antifriction bearing 20 carried by the closed end of the bell-shaped casing portion 10 and its opposite end secured to the central hub 22 of a centrifugal weight carrying member 21. The hub 22 is adapted to be secured to and driven by a rotating shaft of the engine or device, not shown, to which the governor is applied. The central hub 22 of the centrifugal weight carrier is flanked by two atent O i Patented May 27, 1958 parallel axially extending winged support members 24 and 26 carrying pivot pins 28 and 30 between them in equidistant spaced relation to the shaft 18. Centrifugal weights 32 and 34 are pivoted on the pins 28 and 39, respectively, to swing outwardly in response to speed and are provided with inwardly extending cam lugs or crank arms 35 and 36. A riser sleeve 38 slidably carried by the shaft 18 has an annular flange or washer member 40 in thrust engagement with the cam lugs 35 and 35. The opposite end of the sleeve 38 is provided with an antifriction thrust bearing 42 which is adapted to engage a forked or yoked member 4 suitably secured on the lower end of the vertical shaft 46.

The shaft 46 is suitably journalled within the casing, as shown at 48 and 50, and extends through the tubular portion 14 of the casing. As shown in Figures 1. and 2, a bell crank lever 52 is secured to the upper end of the shaft 46 and is adapted to oscillate as the shaft 46 is turned by the action of the centrifugal weights 32 and 34' upon the sleeve 38 and the yoke 44. One arm 54 of the bell crank lever 52 carries an adjusting screw 74 adapted to engage a plunger element 76 reciprocably mounted by a bracket 78 formed integrally with the casing. The plunger 76 has an annular flange 84 which serves as a spring seat for one end of a helical speeder spring 82 which is arranged in concentric relation around the plunger. The opposite end of the speeder spring 82 is seated against a hydraulically actuated piston which is reciprocably mounted in a cylinder 34 of a servo control mechanism which is discussed below. The spring biases the piston towards the closed end of the cylinder and biases the annular flange 3% of the plunger 76 towards the mounting bracket 78 and maintains the plunger in thrust relation to the adjusting screw 74.

The other arm 53 of the lever 52 carries a pin 56 on which a floating lever 58 is pivotally mounted. Que end of the floating lever carries a pin 70 which is linked to the engine fuel control rack, not shown, by the link 71. The other end of the floating lever has a slot 60 engaging a pin 62 which may be adjusted to lock the fuel control linkages in either an engine 0 or running position. The pin 62 is carried by the plate 64 eccentrically of the control shaft 66 which is mounted in a detachable cover 68 for the upper casing 12.

in the embodiment of. our invention shown in Figure 2, the servo control mechanism designated generally by the numeral 81 is designed to be substituted for a manually adjustable speeder spring seat (not shown) and includes a cylinder 84 having an end threadedly secured in the opening 33 formed in the upper casing portion 12, which opening 83 previously served for locating the manually adjustable seat. in such an installation the cylinder 84 is aligned with the plunger '76 and, while shown as detachably secured to the opening at one end, could obviously be formed integrally with the upper casing portion. The cylinder is closed at its opposite end by suit able means such as the head 86 and has a pressure fluid inlet 38 intermediate its ends which is connected to some 5 is of suflicient axial width to be in continuous 'com'.

munication with the fluid inlet 88 through the entire stroke of the piston. A second passage 98 in the body of the piston 96 serves as a pressure relief conduit interconnecting the chamber 91 with the bore 92 for relieving. pressure in the chamber 91. The passage 9% has an axialeI passages 94 and 93, respectively.

1y extending portion connected to a. radially extending portion which opens into the bore 92 axially of the pressur passage as and away from the pressure chamber 91.

A metering valve 166 is reciprocably mountedlin the a. passageway between'the stem and the bore 92 connecting the pressure relief passage 98 to the interior. of the casingp The bore 92 may also be enlarged by counterboring about the valve stem as'shown at 193 to provide an enljargedrelief passageway. The valve stem 102 may be adjustably secured to the plunger 76 'by means of a threaded engagement as shown at 194 and locked in its adjusted position by means of a lock nut 105. The end of the valve 100 may be provided with a wrench socket or slot whereby minor adjustments in the valve setting may be made through the opening 106 formed in the head 36 opposite the bore' 92 after removal of the drain plug 107. 5

From the foregoing description it is believed thatthe operation of the governor will be readily apparent. As-

suming that the engine'is running and that the pin 62 has been set at the engine running position, governing of the engine speed is afiected by the tendency of the weights 32 and 34 to swing outwardly about their pivots 28 and dueto the inertia forces caused by the ex- .cessive rotational speed of the centrifugal weight carrier 21. This outward swinging of'the weights causes the sleeve 38 to move axially to the left (as viewed in Figure 1) through the cam action of the lugs 35 and 36' upon the annular flange 40 and maintains the thrust bear- 7 ing 42 in engagement with the forked'member 44. This rotates the shaft 46 in opposition to the speeder spring 82 acting through the plunger 76' and the crank'arm 54; If thefspring seat opposite the plunger were fixed relative thereto, as by the manually adjustable spring seat, the governor would have a positive droop characteristic. That is, it would efiect a decrease in engine speed with an increase in load. tends to modify the force applied by the vs'peeder spring 82 on the plunger 76 thereby controlling the droop characteristics of the governor. a

The oscillation of the crank arm 54 with the shaft 46 in response to the action of the centrifugal weights causes axialshifting of the plunger 76 and the valve 100 to control the admission or relief of hydraulic pressure fluid to or from the pressure chamber 91 by the hydraulic fluid inlet or relief ports 94 or 98, respectively, opening into the bore 92 of the piston 9% This admission and relief of pressure fluid from the pressure chamber 91 results in axial movement of the piston 99 in response to the movement of the plunger 76 thereby controlling the biasing force which the speeder spring 82 exerts on the plunger. The axial movement of the piston 90 also serves to close the inlet or relief port, as the case may be, thereby limiting the movement'of the piston. If

the piston were to over-travel, the opposite port would 4 governor weights allow the. ,speeder spring to return the plunger 76 toward the rightdecreasing the force on the speeder spring, but as this has theconsequent eifect of closing the piston relief port 98 and of uncovering the pressure port.94, the spring force is maintained constan by movement of the piston likewise to the right. 7

Due to the geometry of the weights, the force applied to the speeder spring increases as the. weights move outwardly with increasing engine speed. As a. consequence of maintaining a-constant spring force in opposition to the movement'of the weights, an increase in engine'speed results with an increased engine load at the governed setting. This will be seen from the .fact that since the spring force is sufiicient to balance the greater force of the weights in their outwardly swung position for that speed corresponding. to no-load engine operating condition, this same spring force enables the engine to operate at a higher'speed under full load in balancing the force of the weights in the collapsed position cor-,

.. our invention are readily accesisble without removal from the governor or governed device and that such a servoclaims without departing from the spirit of the invention.

We claim:

1. in a governorfor controlling an op'eratin g condition of va device associated therewith, a' casing including a cylinder closed at one end, said cylinder havingian inlet The scrvo control of our invention forpressure fluid intermediate its ends,ia piston reciprocable within said. cylinder 'and forming an "expansible chamber therebetween, said piston having an axialbore therethrough, a metering valve 'reciprocable within the bore ofsaid piston, a part drivably connected to said valve and movable within s'aidcasing in response. to change in said operating condition, linkage means associated with said part and operable to control said operating condition in accordance with the movementv thereof, a spring reacting between said piston and said-valve and biasing said piston away, from said part toward the tive positions of thevalve and piston to alternativelyconbe uncovered, and the piston would be returned to its f proper position relative to the valve 106.

Inthe instant embodiment, the force exerted by the speeder spring 82 on the plunger 76 is maintained con:

stant at all times by. the servo control irrespective of the engine operating load. Upon a decrease in'engine oper- V spring 82, but as this has the consequent effect of uncovering the piston relief port 98, the increasing spring force is relieved by movement of the piston likewise to, w

the left. As a result'the load on the Speeder spring remains constant. Upon an'increase in engine operating load,- due'to the resulting decrease in engine speed, the' nect said inlet to said chamber and .said chamber to the interior of said casing whereby the piston is actuated in accordance with the position of said partto control the biasing force of said spring on said part.

2. In a governor for controlling an operating condition. 'of a device associated therewith, a casing including a cylinder closed at one end, said'cylinder having an inlet for pressure fluid intermediate its ends, a piston reciprocable within said cylinder and forming an expansiblc chamber operative condition and including a part movable within said casing in response to Ichangein said operating condition, a plunger element reciprocablymounted withinsaid casing in thrust relation to said part and connected to said valve stem portion, a springreactingbetwecn said piston and said plunger and biasing said'plunger and valve towards said part and biasing said piston toward the closed endof said cylinder, and meanscontrolled by the relative positions, of'the valve and piston'whereby the piston is actuated in accordance with the position of said part to control the biasing force of said spring, said means including a first passage in said piston connecting said inlet with the end of said bore opening on said chamber for introducing pressure fluid to said chamber and a second passage connecting said chamber to the opposite end of said bore and to said passageway and forming a pressure relief outlet with said passageway from the chamber to the interior of said casing.

3. In a governor for an internal combustion engine or the like, a cylinder closed at one end and having a pressure fluid inlet intermediate its ends, a piston reciprocable within said cylinder and forming an expansible chamber therebetween, said piston having a bore extending therethrough, a first passage formed in said piston and connecting. said inlet with said bore for introducing pressure fluid to said chamber, a second passage formed in said piston and interconnecting said bore and said chamber for relieving of pressure within said chamber, a metering valve reciprocable within said bore having a reduced stem portion in radially spaced relation to said bore and forming a passageway connecting said second passage to the exterior of said cylinder, means operable to control the speed of said engine including a speed responsive part movable relatively of said cylinder, a plunger element in thrust relation to said part and connected to said stem, and a spring compressively interposed between said piston and said plunger whereby said plunger and valve are biased towards said part and the piston is biased toward the closed end of the cylinder, said first and second passages being controlled by the relative positions of the valve and piston whereby the piston is actuated in accordance with the position of said speed responsive part to maintain the bias on said part relatively constant irrespective of the load imposed on said engine.

4. In a governor for an internal combustion engine or the like, a casing including a cylinder closed at one end, said cylinder having an inlet for pressure fluid intermediate its ends, a piston reciprocable in said cylinder and forming an expansible chamber with said closed end, said piston having an axial bore therethrough, a pressure passage formed in said piston and interconnecting said in et and said bore for introducing pressure fluid into said chamber, a pressure relief passage formed in said piston and interconnecting said chamber with said bore in spaced relation from said pressure passage and away from said closed cylinder end, a metering valve reciprocable in said bore having a reduced stem portion in radially spaced relation to said bore and adapted to form a fluid connection between said relief passage and the interior of said casing, linkage means operable to control the speed of said engine and including a speed responsive part movable axially of said cylinder, a plunger element in thrust relation to said part and connected to said valve,

and a spring compressively interposed between said piston and said plunger and biasing said plunger and valve toward said part and biasing the piston toward the closed end of the cylinder, said pressure and relief passages being controlled by the relative positions of the valve and piston whereby the piston is actuated in accordance with the position of said part to maintain the biasing force of the spring on said part substantially constant irrespective of the load imposed on said engine.

5. In a governor for an internal combustion engine or the like, a casing having a speed responsive part mounted for movement therein, means associated with said part and operable to control the speed of said engine, said casing having an opening opposite said part, a cylinder aligned with said opening and detachably secured to said casing at one end, said cylinder being closed at its opposite end and having a pressure fluid inlet intermediate its ends, a piston reciprocable in said cylinder and forming an expansible chamber with said closed end, said piston having a bore extending axially therethrough, a pressure passage formed in said piston interconnecting said inlet and said bore for introducing pressure fluid into said chamber, a pressure relief passage formed in said piston interconnecting said chamber with said bore for relieving pressure in said chamber, said relief passage opening into said bore in spaced relation from said pressure passage and away from said closed cylinder end, a metering valve reciprocable in said bore having a reduced stem portion in radially spaced relation to said bore and forming a fluid connection therewith between said relief passage and the interior of said casing, a plunger element in thrust relation to said part and adjustably connected to said valve stem portion, an abutment member within said casing reciprocably mounting said plunger and limiting movement of said plunger to- Ward said part, and a resilient means interposed between piston and said plunger and biasing said plunger and valve toward said part and abutment and biasing said piston toward the closed end of the cylinder, said resilient means encompassing said plunger and valve, and said pressure and relief passages being controlled by the relative positions of the valve and piston whereby the piston is actuated in accordance with the position of said part to maintain the biasing force of said resilient means substantially constant irrespective of the load imposed on said engine.

References Cited in the file of this patent UNITED STATES PATENTS 1,986,415 Schmidt Jan. 1, 1935 2,373,684 Holloway Apr. 17, 1945 FOREIGN PATENTS 114,836 Great Britain 1919 

